sheepskin

A soft, porous leather produced from the skins of
wooled or hair sheep. It is usually
vegetable-tanned and grained in imitation of other
(more expensive) skins, e.g., morocco, a process
to which it lends itself very well. The term
"sheepskin" always indicates an unsplit skin, and
is not applied to split sheepskin or SKIVER . Split
sheepskin is the traditional material used in
producing PARCHMENT .

Sheepskin is somewhat difficult to describe
because the individual skins differ so greatly in
size, fat content, and general quality of the
dermal network. From the standpoint of leather,
the closer a sheepskin approaches the hair sheep,
the tighter and firmer the fiber network, and,
therefore, the better the skin for producing
leather. This is the case because the numerous
fine wool fibers, as opposed to the lesser number
of coarse fibers of the hair sheep, cause the skin
to be more open and loose in texture. In addition,
the wool follicles are associated with extensive
glandular structures, consisting of sebaceous and
sudoriferous glands, which also interrupt the
dense packing of the connective-tissue fiber
network in the papillary layers, as well as the
dermis itself.

The grain layer of sheepskin occupies more than a
half of the total thickness of the skin;
furthermore, in the reticular layer, the collagen
fibers are not as compact and run in more closely
horizontal directions.

The proportion of adipose tissue to collagen
fibers in sheepskin varies widely according to the
feeding of the animal. There is frequently an
almost continuous layer of fat cells separating
the grain layer and the reticular layer. Because
much of the fatty tissues is destroyed or removed
in the liming, bating, and scudding operations, it
is not unusual to find the grain layer and
reticular layer of sheepskin leathers separated,
sometimes over wide areas. The tanner at times
separates these two layers by splitting after
liming, and then tans the grain layer for
bookbinding purposes, etc., and the reticular
layer for chamois.

During the beamhouse operations. the glands in the
grain layer are destroyed, leaving the grain layer
rather spongy in structure. This, together with
the relatively loose and empty structure of the
reticular layer, places sheepskin leather in a
class by itself.

Sheepskin is a reasonably durable leather if
properly prepared and cared for. It has been used
as a covering material for books for more than 500
years. See also: LAW
SHEEP ;ROAN
;SKIVER ;SMYRNA MOROCCO .